The subject matter disclosed herein relates generally to magnetic resonance imaging systems and, more particularly, to baluns for radio frequency coils in magnetic resonance imaging systems.
Magnetic resonance imaging (MRI) systems enable imaging based on a primary magnetic field, a radio frequency (RF) pulse, and time-varying magnetic gradient fields that interact with specific nuclear components in an object, such as hydrogen nuclei in water molecules. The magnetic moments of such nuclear components may attempt to align with the primary magnetic field, but subsequently precess at a characteristic frequency known as the Larmor frequency. An RF pulse at or near the Larmor frequency of such nuclear components may cause the magnetic moments to be rotated. When the RF pulse has ended, the magnetic moments may attempt to realign with the primary magnetic field, emitting a detectable signal.
The RF pulse is produced by a radio frequency coil based on radio frequency signals received from control circuitry. The control circuitry may generally transmit the radio frequency signals across coaxial cables to the radio frequency coil. Because coaxial cables provide for unbalanced transmission while the radio frequency coil may provide for balanced transmission, a coaxial balun may transform balanced signals to unbalanced, and vice versa. However, such coaxial baluns may be relatively large and may transform signals being received from or transmitted across coaxial cables, but not other transmission means.